Heretofore, the known rotary actuators utilized an air driven piston and cylinder drive assembly for driving a pinion gear operatively connected to a rotary plate. In such known actuators, the angular rotation of the rotary plate was determined by the piston engaging a stop to limit the stroke of the piston and thus determining the degree of angular rotation of the rotary plate. However, it has been noted that abruptly limiting or stopping the stroke of the piston by a stop imposed severe impact on the meshing gear teeth of a complementary pinion gear and associated piston rack which, over time, introduced considerable play or backlash and/or damage to the meshing gear teeth to result in greatly reducing the accuracy or precision of the rotary actuator and/or the useful life of the rotary actuator.